How can I extrapolate the mean from data ranges, assuming normal distribution? [closed]

I have the following summary of data point values:

Under 600: 38%
601-800: 51%
Over 801: 11%

Assuming a normal distribution of values, how can I calculate the mean?

Note: it doesn't have to be precise, just a rough estimation to the nearest 10 would be sufficient.

Many thanks!

closed as off-topic by Michael Chernick, kjetil b halvorsen, mdewey, Stephan Kolassa, Peter Flom♦Oct 16 '17 at 12:22

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "Self-study questions (including textbook exercises, old exam papers, and homework) that seek to understand the concepts are welcome, but those that demand a solution need to indicate clearly at what step help or advice are needed. For help writing a good self-study question, please visit the meta pages." – Michael Chernick, kjetil b halvorsen, mdewey, Stephan Kolassa, Peter Flom
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• This reads like a routine textbook exercise ... is this an exercise for some class? – Glen_b Oct 15 '17 at 20:32
• Since this seems like homework, here's a hint. The median is the same as the mean in a normal distribution. – Peter Flom Oct 16 '17 at 12:22
• No the reason I am asking this question is that I have access to some room rental data from a lettings website and while they don't show the average room price they do show room prices ranges (as listed in the question). So assuming normal distribution (which isn't a correct assumption but workable given the context) I wanted to know what formula I can use to calculate the mean. If there's some other way in which I am meant to ask the question please let me know. – Charlie Reay Oct 17 '17 at 9:12